They have kinda always been a thing. Nazi’s were just one flavor of nationalist, after all.

Charles de Gaulle defined nationalism best: “Patriotism is when love of your own people comes first; nationalism, when hate for people other than your own comes first.”

For most people, it’s extremely easy to blame others for problems of their own creation. By the same token, people who can’t see their own shortcomings will also usually latch on to leaders who are able to amplify that bias. For the Nazis, it was mostly against the jews.

Also, what you are seeing in the news is partially amplified by the news itself but also, politicians are getting more brazen in mustering the support of those groups. This has lead to people being a little more open about something that needs to stay taboo, IMHO.